CN103453752B - A kind of low energy consumption brown coal drying technique and equipment thereof reclaiming brown coal moisture - Google Patents

Abstract

The present invention relates to brown coal drying and comprehensive high-efficiency utilizes technical field, disclose a kind of the low energy consumption brown coal drying technique and the equipment thereof that reclaim brown coal moisture.Drying equipment of the present invention comprises the drier utilizing steam indirect, and brown coal drying process is: take steam as heat medium, and this steam enters brown coal in drier and drier and carries out dry heat exchange; The moisture simultaneously deviate from brown coal is heated to form indirect steam, and this indirect steam realizes gas solid separation by the outer tube be made up of porous gas solid separation material, discharges outside drier, reclaims to be utilized.The present invention can not only reclaim the moisture removed from brown coal, can also reduce the energy ezpenditure in dry run simultaneously, thus improves energy utilization efficiency, the level of resources utilization and the environmental benefit of brown coal comprehensive utilization project.

Description

A low-energy lignite drying process and equipment for recovering lignite moisture

technical field

The invention relates to the technical field of lignite drying and its comprehensive high-efficiency utilization, in particular to a drying process and equipment for lignite with high water content.

Background technique

Lignite is a kind of coal with high volatile content (about 50%), high moisture content (above 30%), and low calorific value (about 14MJ/kg). Because of its low calorific value, easy spontaneous combustion, and unsuitable for long-distance transportation, lignite has long been regarded as a low-quality coal resource. Worldwide, the development and utilization of lignite is not high. In China, lignite is currently mainly used as fuel for pit-mouth power plants and raw materials for pit-mouth gasification.

China is rich in lignite resources, with proven reserves of 130.3 billion tons, accounting for about 13% of the country's coal reserves, mainly concentrated in Inner Mongolia, Heilongjiang and Yunnan provinces, among which Inner Mongolia has the largest lignite reserves, accounting for 77% of the country's lignite reserves %. Therefore, rational development and full utilization of lignite resources in water-shortage areas and improvement of the comprehensive utilization value of lignite is an important field for realizing the strategic goal of national energy security.

Pre-drying and drying is the first step for lignite to be used as boiler fuel or gasification raw material or other deep processing raw materials. In order to meet the process requirements, the pneumatic conveying of lignite needs to remove surface water. Therefore, lignite needs to be dehydrated in the lignite conversion process accompanied by fluidization and pneumatic conveying process, such as large boiler fuel and fluidized bed, entrained bed raw material.

The conversion of lignite after dehydration is not only a process requirement, but also can greatly improve energy utilization efficiency and environmental protection benefits. Take it as a boiler fuel as an example: when lignite with a water content of 35wt% and a calorific value of 12MJ/kg is dried to reduce the moisture content in the lignite to 9wt%-12wt%, its calorific value can be increased to 16-18MJ/kg. It is equivalent to a 45% to 55% increase in the calorific value of lignite. At this time, when used as fuel, the net efficiency of the boiler increases by 2% to 2.8%, the amount of fuel decreases by 8% to 11%, and the amount of flue gas decreases by 3% to 4%. After drying, it can be used as boiler fuel, which can greatly improve energy utilization efficiency and environmental protection benefits.

When lignite is used as a raw material for gasification, reducing the water content can greatly reduce the consumption of oxygen and coal consumption. For example, lignite is gasified by entrained bed. When the water content in the gasification raw material is reduced by 1%, the oxygen consumption per unit of effective gas will be reduced by about 0.65%. , the effect is significant. Reducing the water content of the raw material can effectively increase the effective gas content in the gasification product, which means that the asset utilization efficiency of the gasification device with high investment intensity is improved. Therefore, the pre-drying and drying of lignite is a very important step for the conversion project of lignite comprehensive utilization.

Lignite drying consumes a lot of energy, which is the most energy-consuming process in the whole process of lignite comprehensive utilization projects. The pre-drying process for the purpose of removing surface water requires 1.42 to 1.8 tons of low-pressure steam to remove 1 ton of water, which is equivalent to More than 10% of raw lignite is used for its own moisture removal. Lignite deep processing and conversion projects are also projects with high water consumption intensity. A coal-based olefin project with a lignite processing capacity of 10 million tons per year consumes about 20 million tons of water resources per year. In the construction of lignite conversion projects in water-deficient areas, the lack of water resources has become an important restrictive factor for the comprehensive utilization of lignite.

All current drying and pre-drying methods, including tube dryer drying, rotary drum drying, and steam fluidized bed drying, cannot effectively utilize the energy of the secondary steam produced by drying, so the energy utilization efficiency of the drying process is low; currently all Drying and pre-drying methods, except for steam fluidized bed drying, cannot effectively recover the moisture removed from lignite during the drying process.

Contents of the invention

The invention aims at the deficiencies of the prior art, and aims to provide a low-energy-consumption lignite drying process and equipment thereof for recovering lignite moisture. The invention can recover the moisture removed from the lignite during the drying process, and reduce the energy consumption during the drying process, thereby improving the energy utilization efficiency, resource utilization efficiency and environmental protection benefit of the lignite comprehensive utilization project.

A low-energy lignite drying equipment for recovering lignite moisture, comprising a drier indirectly heated by steam, the drier includes a drier wall, an outer casing, and an inner casing type steam condensation heating element, and the outer casing is all or partially Made of porous gas-solid separation material, the wall of the dryer is provided with a steam inlet, a steam outlet, and a water outlet. After heat exchange, the lignite is cooled into liquid and discharged through the water outlet on the wall of the dryer. The lignite flows from top to bottom between the inner sleeve type steam condensation heating element and the outer sleeve, and the lignite is heated and dried. Afterwards, secondary steam is generated, and the secondary steam is separated from gas and solid through the outer casing, and then discharged through the steam outlet on the wall of the dryer, and recovered for use.

In the above solution, the dryer is a single-layer dryer or a multi-layer dryer.

In the above solution, the porous gas-solid separation material is a sintered metal material, a ceramic material, a composite material of sintered metal and ceramics, or a polytetrafluoroethylene material.

In the above scheme, the inner casing type steam condensing heating element is an inner casing type steam condensing heating element with a closed upper end, the steam flows from bottom to top in the inner tube, turns back to the upper end of the inner tube, and then flows from the annular gap of the inner tube to the inner tube. Flow up and down.

In the above solution, the outer wall of the inner casing type steam condensation heating element can be designed as various forms of outer finned tubes, and the angle of the fins should ensure the downward flow of lignite pellets.

In the above solution, a lignite feeding device and a uniform distribution device are provided on the top of the dryer, and a lignite uniform discharge device is provided at the lower part.

A low-energy lignite drying process using the drying equipment to recover lignite moisture. The drying process is as follows: using steam as the heating medium, the steam enters the drier and the lignite in the drier for drying and heat exchange, and the lignite is heated and dried ; Simultaneously, the indirect heat exchange drier heats the moisture detached from the lignite into secondary steam, and the secondary steam is separated from gas and solid through the outer sleeve made of porous gas-solid separation material, and is discharged through the steam outlet of the drier, and is recovered for later use. use.

In the above scheme, the recovery and utilization of the secondary steam has the following three methods, which are respectively:

a) The secondary steam is cooled by indirect air cooling or other methods, and the moisture removed from the lignite is recovered after cooling; this method has a simple process and saves investment, and is suitable for projects with excess low-pressure steam. Due to the low content of inert gas in the secondary steam, most of it is condensed into liquid after being indirectly cooled by air cooler or other methods, the moisture from lignite drying is recovered, and the inert gas is discharged from the separator behind the air cooler.

Or b) use the secondary steam booster equipment to boost the secondary steam and reuse it as a drying heat source; this method uses the heat pump principle and has the highest energy utilization efficiency, but increases the secondary steam liter in the process. Pressure equipment; the secondary steam drawn from the dryer is boosted to 2-5 bar, mixed with supplementary low-pressure steam, and reused as a heat source for indirect heating and drying. The mixed steam is condensed into condensate during the lignite drying process, and then the inert gas is discharged through the steam trap, and the condensate is recovered.

or c) adopt the non-equal pressure multi-stage series drying process setting, and use the secondary steam generated by the higher pressure dryer as the heat source of the next pressure dryer; the secondary steam generated by the final dryer is passed through the indirect air Cooling or cooling in other ways to recover the moisture removed by drying in the lignite; this method utilizes most of the latent heat of the secondary steam, which greatly reduces the energy consumption of the drying process, and at the same time reduces the configuration of the secondary steam booster ;In this process, the pressurized dryer adopts lock hopper feeding and discharging;

A typical non-isobaric three-stage drying example is: the first-stage drying pressure is 7-13bar, and the heating steam pressure is 13-25bar. The pressure of the secondary drying is 3~6bar, and the heating steam is the secondary steam from the primary drying. The third-stage drying pressure is 1 normal pressure, and the heating steam is the secondary steam from the second-stage drying.

At the same time, after the secondary steam generated by the primary dryer is used as the secondary drying heat source, it is condensed into condensate and recovered; after the secondary steam generated by the secondary dryer is used as the tertiary drying heat source, it is condensed into condensate and recovered; Most of the secondary steam drawn from the third-stage dryer is condensed into liquid after air cooling or other indirect cooling, the water is recovered, and the inert gas is discharged through the separator.

In the above scheme, the crushed lignite with particle size ≤ 6.3mm is stored in the crushed coal bin, and the lignite in the crushed coal bin is evenly fed to the upper part of the dryer through the feeding and uniform distribution device; the lignite is from top to bottom, through Gravity difference flows downward, is indirectly heated by the steam tube bundle and gradually dried, and the dried lignite is uniformly discharged through the discharge device; the secondary steam generated during the drying process is led out of the dryer through the gas-solid separation element.

Wherein, the drying degree of the lignite is controlled by controlling the feeding and discharging speed of the lignite, and the moisture content of the lignite after drying is controlled at 8wt%-12wt%.

Beneficial effects of the present invention:

(1) The present invention adopts steam indirect heating, avoids the leakage of inert gas in the drying process, the content of inert gas in the secondary steam is low, and the usable value of the secondary steam is high.

(2) The drying equipment used in the present invention is simple in structure, and the drying process is accompanied by the separation of secondary steam. The present invention can not only reclaim the moisture removed from lignite, but also reduce energy consumption in the drying process, thereby improving the comprehensive efficiency of lignite. Utilize the energy efficiency, resource efficiency and environmental benefits of the project.

(3) In the present invention, since the content of inert gas in the secondary steam is low and the partial pressure of the steam is high, the moisture produced by drying can be recovered by simple cooling, which is of great value for saving water resources in water-deficient areas.

(4) In the present invention, by boosting the secondary steam as a drying heat source and reusing it, or using three-stage differential pressure drying, the consumption of steam for external use can be effectively reduced, and after the secondary steam is used as a drying heat source to complete heat exchange and condensation, the condensate Can be recycled.

(5) The present invention is suitable for lignite drying of lignite fuel boilers, pre-drying of entrained-bed gasification of lignite as raw material, drying of fluidized-bed gasification, and lignite pyrolysis upgrading.

Description of drawings

Figure 1 is the drying process for recovering dry water, where X02001 is a dryer, C02001 is an induced draft fan, M02001 is a bottom agitator, V02001 is a separation tank, X02002 is a conveyor, V02002 is a separation tank, E02001 is an air cooler, and 1 is a crushed coal Feeding pipeline, 2 is the pipeline of low-pressure superheated steam from the outside, 3 is the non-condensable gas discharge pipeline, 4 is the recycling pipeline of condensate, and 5 is the dry coal transportation pipeline.

Figure 2 is the drying process of reusing the secondary steam as a drying heat source and recovering dry moisture, where X02001 is the dryer, C02002 is the steam compressor, M02001 is the bottom agitator, V02001 separation tank, X02002 conveyor, V02002 1 is the feeding pipeline for crushed coal, 2 is the pipeline for low-pressure superheated steam from the outside, 3 is the non-condensable gas discharge pipeline, 4 is the recycling pipeline for condensate, and 5 is the dry coal delivery pipeline road.

Figure 3 is a multi-stage differential pressure drying process, where X02001A, X02001B, and X02001C are dryers, M02001A, M02001B, and M02001C are bottom agitators, V02001 is a separation tank, X02002A, X02002B, and X02002C are conveyors, and V02002A, V02002B, and V02002B are separation tanks. , E02001 is the air cooler, C02001 is the induced draft fan, 1 is the feeding pipeline for crushed coal, 2 is the pipeline for low-pressure superheated steam from the outside, 3 is the non-condensable gas discharge pipeline, and 4 is the recycling pipeline for condensate , 5 is the dry coal delivery pipeline.

Figure 4 is a schematic diagram of a typical multi-layer dryer, where 1 is the steam outlet, 2 is the water outlet, 3 is the steam inlet, 4 is the pulverized coal inlet, and 5 is the dry coal outlet.

Detailed ways

In order to better understand the present invention, the content of the present invention will be further explained below in conjunction with the accompanying drawings and embodiments, but the content of the present invention is not limited to the following examples.

Example 1

This embodiment is a lignite pre-drying process for recovering lignite drying moisture. The lignite processing capacity is 5 million tons per year, and its process flow is shown in Figure 1.

The lignite pre-drying process for recovering dry moisture mainly includes: lignite pretreatment, lignite moving bed pre-drying, secondary steam condensate recovery, and heating steam condensate recovery.

1. Lignite pretreatment system: Lignite with a water-rich content of 15wt% to 55wt% and a coal particle size of ≤300mm from the boundary area enters the raw coal silo, and is sent to the double-roller crushing through the unloading belt conveyor and the feeding belt conveyor. Machine, the double-roll crusher with high-alloy material crushes the material to the size of the gap between the two rolls. The crushed coal particles are less than or equal to 30mm, and the crusher is sent to the silo through the feeding belt conveyor, and the coal particles from the silo enter the relaxation screen, and the coarse coal particles go to the reversible hammer crusher, and are crushed by the high-speed rotating hammer The head hits the impact plate, the coal particles are crushed to ≤6.3mm, mixed with the sieved fine coal particles, and sent to the crushed coal bunker for storage.

2. Pre-drying in the moving bed drying system: the qualified coal particles obtained from lignite pretreatment are removed by indirect drying in this system. The main equipment of the moving bed drying system includes dryer (Figure 1-X02001), bottom agitator (Figure 1-M02001), and conveyor (Figure 1-X02002). Coal particles with a particle size of ≤6.3mm are fed from the top feeding device of the dryer, move from top to bottom in the dryer, and are dried by the heat from the steam tube bundle. After drying, they are discharged from the discharge device at the bottom of the dryer and sent to the downstream process. Among them, the steam tube bundle is externally supplied low-pressure steam, which flows in the tube bundle and performs heat exchange with the lignite outside the tube bundle. After being condensed, the condensate converges and is discharged out of the dryer through the water outlet of the dryer. During the lignite drying process, the moisture contained in the lignite is heated to generate secondary steam, and the secondary steam is separated from gas and solid through the outer casing. After converging, it is discharged from the dryer through the steam outlet of the dryer wall, and then sent to the air cooler equipment (Fig. 1 -E02001). The outer casing is made of sintered metal material (sintered stainless steel powder, copper powder or titanium powder), the heating medium is low-pressure steam, the steam pressure is ≤0.5MPa, and the temperature is 130-180°C. Control the moisture in lignite to 8wt%-15wt% by feeding and discharging speed. The dryer is equipped with a steam blowback system, which periodically backwashes the gas-solid separation element (outer casing).

3. Secondary steam condensate recovery system. The secondary steam from the dryer is condensed and cooled by the air cooler (Fig. 1-E02001), and then passed through the separator (Fig. 1-V02001). The non-condensable gas is evacuated through the separator, and the steam condensate is recovered.

4. Heating medium condensate recovery system. The heating steam is condensed after completing the heat exchange with the lignite, the condensate is collected and discharged from the dryer through the water outlet of the dryer, and then enters the separator (Figure 1-V02002), the non-condensable gas is emptied through the separator, and the steam condensate is Recycle.

Typical process indicators are as follows:

(1) Raw materials and products

—Processing scale: 5 million tons/year

— Moisture content before drying: 34% (ar basis)

— Moisture content after drying: 15% (ar base)

(2) Consumption index

—Supplementary low-pressure steam: 2.06 million tons/year

—Recovery of steam condensate: 1.25 million tons/year

—Equipment power shaft power: 1400Kw

Example 2

This embodiment is a lignite pre-drying process using secondary steam boosting as a drying heat source. The lignite processing capacity is 5 million tons per year, and its process flow is shown in Figure 2.

The lignite pre-drying process with secondary steam boosting as the drying heat source mainly includes: lignite pretreatment, moving bed drying system pre-drying, secondary steam boosting and reuse as heating steam, and recovery of heating steam condensate.

1. Lignite pretreatment system: Lignite with a water-rich content of 15wt% to 55wt% and a coal particle size of ≤300mm from the boundary area enters the raw coal silo, and is sent to the double-roller crushing through the unloading belt conveyor and the feeding belt conveyor. Machine, the double-roll crusher with high-alloy material crushes the material to the size of the gap between the two rolls. The crushed coal particles are less than or equal to 30mm, and the crusher is sent to the silo through the feeding belt conveyor, and the coal particles from the silo enter the relaxation screen, and the coarse coal particles go to the reversible hammer crusher, and are crushed by the high-speed rotating hammer The head hits the impact plate, the coal particles are crushed to ≤6.3mm, mixed with the sieved fine coal particles, and sent to the crushed coal bunker for storage.

2. Pre-drying in the moving bed drying system: the qualified coal particles obtained from lignite pretreatment are removed by indirect drying in this system. The main equipment of the moving bed drying system includes dryer (Figure 2-X02001), bottom agitator (Figure 2-M02001), and conveyor (Figure 2-X02002). Coal particles with a particle size of ≤6.3mm are fed from the top feeding device of the dryer, move from top to bottom in the dryer, and are dried by the heat from the steam tube bundle. After drying, they are discharged from the discharge device at the bottom of the dryer and sent to the downstream process. Among them, the steam tube bundle is the mixed steam of external low-pressure steam and boosted secondary steam, which flows in the tube bundle and exchanges heat with the lignite outside the tube bundle. After being condensed, the condensate converges and is discharged from the dryer through the water outlet of the dryer. During the lignite drying process, the moisture contained in the lignite is heated to generate secondary steam, and the secondary steam is separated from gas and solid through the outer casing, and after converging, it is discharged out of the dryer through the steam outlet of the dryer wall. The outer casing is made of ceramic material (ordinary ceramics), the heating medium is low-pressure steam, the steam pressure is ≤0.5MPa, and the temperature is 130-180°C. Control the moisture in lignite to 8wt%-15wt% by feeding and discharging speed. The dryer is equipped with a steam blowback system, which periodically backwashes the gas-solid separation element (outer casing).

3. The secondary steam is pressurized and reused as a drying heat source. The secondary steam from the dryer passes through the separator (Figure 2-V02001) to remove part of the steam condensate, and then uses the steam compressor (Figure 2-C02002) to increase the pressure of the steam to 3-6bar and returns to the low-pressure steam pipeline , as a heating medium into the dryer.

4. Heating medium condensate recovery system. The heating steam is condensed after exchanging heat with the lignite, the condensate is collected and discharged from the dryer through the water outlet of the dryer, and then enters the separator (Figure 2-V02002), the non-condensable gas is emptied through the separator, and the steam condensate is Recycle.

Typical process indicators are as follows:

(1) Raw materials and products

—Processing scale: 5 million tons/year

— Moisture content before drying: 34% (ar basis)

— Moisture content after drying: 15% (ar base)

(2) Consumption index

—Supplementary low-pressure steam: 680,000 tons/year

—Recovery of steam condensate: 1.25 million tons/year

—Equipment power shaft power: 9960Kw.

Example 3

In this embodiment, a three-stage non-isobaric lignite pre-drying process is adopted. The lignite processing capacity is 5 million tons per year, and its process flow is shown in Figure 3.

The lignite pre-drying process of the three-stage non-isobaric drying heat source mainly includes: lignite pretreatment, lignite moving bed pre-drying, and steam condensate recovery.

1. Lignite pretreatment system: Lignite with a water-rich content of 15wt% to 55wt% and a coal particle size of ≤300mm from the boundary area enters the raw coal silo, and is sent to the double-roller crushing through the unloading belt conveyor and the feeding belt conveyor. Machine, the double-roll crusher with high-alloy material crushes the material to the size of the gap between the two rolls. The crushed coal particles are less than or equal to 30mm, and the crusher is sent to the silo through the feeding belt conveyor, and the coal particles from the silo enter the relaxation screen, and the coarse coal particles go to the reversible hammer crusher, and are crushed by the high-speed rotating hammer The head hits the impact plate, the coal particles are crushed to ≤6.3mm, mixed with the sieved fine coal particles, and sent to the crushed coal bunker for storage.

2. Lignite pre-moving bed drying system: This is a non-isobaric three-stage drying system, including the first-stage pressurized dryer (Figure 3-X02001A), the second-stage pressurized dryer (Figure 3-X02001B), and the third-stage Atmospheric pressure dryer (Figure 3-X02001C), in which the pressurized dryer adopts lock hopper feeding and discharging. The drying pressure of the primary dryer is 7-13bar, and the heating steam pressure is 13-25bar. The drying pressure of the secondary dryer is 3-6bar, and the heating steam is the secondary steam and supplementary steam from the primary drying. The drying pressure of the third-stage dryer is 1 normal pressure, which is the secondary steam and supplementary steam from the second-stage drying.

Qualified coal particles from lignite pretreatment are removed by indirect drying in a non-isobaric three-stage drying system to remove external moisture. Coal particles with a particle size of ≤6.3mm move from top to bottom in the dryer and are dried by the heat from the steam tube bundle. The heating steam from the steam tube bundle is condensed in the tube bundle after heat exchange with lignite. After the steam condensate and non-condensable gas mixture are collected, they are discharged from the dryer. During the lignite drying process, the moisture contained in the lignite is heated to generate secondary steam, and the secondary steam is separated from gas and solid through the outer casing, and after converging, it is discharged out of the dryer through the steam outlet of the dryer wall. The outer casing is made of polytetrafluoroethylene material, and the water in the lignite is controlled to be dehydrated to 8wt%-15wt% by feeding and discharging speed. The dryer is equipped with a steam blowback system, which periodically backwashes the gas-solid separation element (outer casing).

3. Steam condensate recovery system

The heating steam of the primary dryer is condensed after the heat exchange is completed, and the condensate passes through the separator (Fig. 3-V02002A), the non-condensable gas is discharged, and the condensate is recovered; the secondary steam generated by the primary dryer is used as After heating the heat source of the secondary dryer, the steam is condensed into condensate, and after passing through the separator (Figure 3-V02002B), the non-condensable gas is discharged and the condensate is recovered; the secondary steam generated by the secondary dryer is used as a After the heat source of the first-stage dryer is heated, the steam is condensed into condensate, and after passing through the separator (Fig. (Figure 3-E02001) After indirect cooling, it passes through the separator (Figure 3-V02001), part of the non-condensable gas is discharged, and the condensed liquid is recovered.

Typical process indicators are as follows:

(1) Raw materials and products

—Processing scale: 5 million tons/year

— Moisture content before drying: 34% (ar basis)

— Moisture content after drying: 15% (ar base)

(2) Consumption index

—Supplementary low-pressure steam: 1.2 million tons/year

—Recovery of steam condensate: 1.25 million tons/year

—Equipment power shaft power: 1500Kw.

Example 4

This embodiment is the basic structure of a typical dryer, and the specific schematic diagram is shown in FIG. 4 .

As shown in the figure, the drier is a drier heated indirectly by steam. The drier includes a drier wall, an outer sleeve, and an inner sleeve type steam condensation heating element. The outer sleeve is entirely or partially made of sintered metal It is made of a material composited with ceramics (one layer of metal and one layer of ceramics composite material), and the wall of the dryer is provided with a steam inlet, a steam outlet, and a water outlet, and the steam flows in the inner sleeve type steam condensation heating element , after heat exchange with the lignite outside the inner sleeve type steam condensing heating element, it is cooled into liquid and discharged through the water outlet on the wall of the dryer. Flowing upwards and downwards, the lignite is heated and dried to generate secondary steam. The secondary steam is separated from gas and solid through the outer casing, and then discharged through the steam outlet on the wall of the drier for recycling.

The dryer can be a single-layer dryer or a multi-layer dryer, and the one shown in Figure 4 is a multi-layer dryer; the inner sleeve type steam condensation heating element is an inner sleeve type steam condensation heating element with a closed upper end , the steam flows from bottom to top in the inner tube, turns back to the upper end, and then flows from top to bottom through the inner ring gap; the top of the above-mentioned dryer is equipped with a lignite feeding device and a uniform distribution device, and the lower part is provided with a uniform discharge device.

Apparently, the above-mentioned embodiments are only examples for clear illustration, rather than limiting the implementation. For those of ordinary skill in the art, other changes or changes in different forms can be made on the basis of the above description. It is not necessary and impossible to exhaustively list all the implementation manners here. However, the obvious changes or modifications thus extended are still within the scope of protection of the present invention.

Claims (9)

1. A kind of low energy consumption lignite drying equipment that reclaims lignite moisture, it is characterized in that comprising the drier that utilizes steam indirect heating, described drier comprises drier wall, outer casing and inner casing type steam condensation heating element, described All or part of the outer casing is made of porous gas-solid separation material. The wall of the dryer is provided with a steam inlet, a steam outlet, and a water outlet. The steam flows in the inner casing type steam condensation heating element, and the inner casing type The lignite outside the steam condensing heating element is cooled into liquid after heat exchange, and is discharged through the water outlet on the wall of the dryer. After being heated and dried, secondary steam is generated, and the secondary steam is separated from gas and solid through the outer casing, and then discharged through the steam outlet on the wall of the dryer, and recovered for use. The porous gas-solid separation material is sintered metal material , ceramic materials, sintered metal and ceramic composite materials, or polytetrafluoroethylene materials. 2. The drying equipment according to claim 1, characterized in that the dryer is a single-layer dryer or a multi-layer dryer. 3. The drying equipment according to claim 1, characterized in that the inner sleeve type steam condensation heating element is an inner sleeve type steam condensation heating element with a closed upper end, and the steam flows from bottom to top in the inner tube to the upper part of the inner tube The end turns back and then flows from top to bottom through the inner casing annulus. 4. The drying equipment according to claim 1, characterized in that the outer wall of the inner casing type steam condensation heating element is an outer finned tube, and the angle of the outer finned tube is an angle that can ensure the downward flow of lignite pellets. 5. The drying equipment according to claim 1, characterized in that the top of the drier is provided with a lignite feeding device and a uniform distribution device, and the lower part of the drier is provided with a uniform discharge device. 6. A lignite drying process utilizing the drying equipment described in any one of claims 1 to 5, characterized in that the drying process is: using steam as a heating medium, the steam enters the drier and the lignite in the drier for drying and heat exchange, The lignite is heated and dried; at the same time, the moisture detached from the lignite is heated into secondary steam by using a drier indirectly heated by steam. The steam outlet of the wall is discharged and recovered for use. 7. according to the described drying process of claim 6, it is characterized in that described secondary steam has the following three ways of recycling: a) secondary steam is cooled by air cooler or other ways, and moisture is recovered after cooling; or b ) Use steam booster equipment to boost the secondary steam and reuse it as a drying heat source. After the reused secondary steam completes heat exchange, condensed water is obtained, and the condensed water is recovered; or c) non-isobaric multi-stage series In the continuous setting, the secondary steam generated by the higher pressure dryer is used as the heat source of the intermediate pressure dryer, the secondary steam generated by the intermediate pressure dryer is used as the heat source of the normal pressure dryer, and the secondary steam of the last stage dryer is used as the heat source of the intermediate pressure dryer. Cool and condense to recover water or use it as other low-temperature heating heat source. 8. The drying process according to claim 7, characterized in that the secondary steam is pressurized to 2-5 bar and reused as a drying heat source. 9. The drying process according to claim 7, characterized in that the non-isobaric multi-stage series connection is set as follows: the primary drying pressure is 7-13 bar, the heating steam pressure is 13-25 bar; the secondary drying pressure is 3-25 bar. 6bar, the heating steam is the secondary steam from the primary drying; the pressure of the tertiary drying is normal pressure, and the heating steam is the secondary steam from the secondary drying; at the same time, the secondary steam generated by the primary dryer is used as the secondary drying After the heat source, it is condensed into condensate and recovered; the secondary steam generated by the secondary dryer is used as the tertiary drying heat source, condensed into condensate and recovered; the secondary steam drawn from the tertiary dryer is cooled by air or other methods After indirect cooling, the moisture is recovered.